120 GEODIA AGASSIZII. 



DIMENSIONS OF LARGE CHOANOSOMAL AMPHIOXES OF GEODIA AGASSIZII.' 



The large, thick, club-shaped styles (Plate 28, figs. 12-14), which occur in 

 small numbers in the specimens from Stations 3168 and 4193, are straight or 

 slightly curved, always thickened at the rounded end, and 115-145 /i thick. 



The minute dermal amphioxes (Plate 27, figs. 3a, 7a, 8a) occur in all speci- 

 mens. They are slightly curved and usually not very sharply pointed at the 

 ends. Sometimes one end is much more blunt than the other, but the bluntness 

 never seems to be great enough to make the spicule appear as a style. In the 

 adult specimens these spicules are 160-480 fi long and 5-12 /i thick, their average 

 maximum dimensions being 342 X 9.06 p.. Those of the specimens from Station 

 2886 are considerably larger, both longer and thicker, than those of the others. 

 Particularlj' slender ones are met with in the adult specimen from Station 4228. 

 In the young specimen from Station 4228 these spicules are 225-300 p long 

 and 4-7 p thick. In the immature specimen described by Lambe they are 180- 

 480 by 3-8 p. 



DIMENSIONS OF SMALL DERMAL AMPHIOXES OF GEODIA AGASSIZII. 



•In this and the following tables the specimen from Station 4228 is a young specimen; those from the other 

 stations are adults. 



